In early March, Indigenous Honduran activist Berta Caceres was gunned down in her own home in response to her protests against a dam that threatens to displace hundreds of her people. A few weeks later, another member of her community, Nelson Garcia, was murdered for the same reason.

Berta received the Goldman Environmental Prize in 2015 in recognition of her efforts, and was an inspiration to Indigenous Peoples around the world. During my official visit to Honduras last November, she facilitated my meeting with her people, who told me troubling stories of violence and intimidation in response to their protests.

Despite numerous death threats and emergency protection measures granted by the Inter-American Commission for Human Rights, the Honduran government failed to protect Berta, and continues to fail her community. Her family and her community remain in danger, and it is urgent that the government – who has thus far maintained that Berta's murder was a botched robbery – act immediately to protect her family and stem the flow of indigenous blood.

Sadly, Berta and Nelson's story is far from unique. On my recent trip to Brazil, numerous Indigenous Peoples told me of the intimidation, threats, and outright violence they have faced for standing up for their land rights. According to Global Witness, 29 of the environmental activists murdered in 2014 were from Brazil, more deaths than were reported in any other country. At least 454 persons have been killed for environmental activism and assertion of Indigenous Peoples' rights in Brazil since 2002. And, judging by many metrics, Brazil is a "leader" on Indigenous Peoples' rights.

In Mato Grosso do Sol, indigenous Guarani Kaoiwa communities face constant attacks and evictions from landlords seeking to develop industrial-scale farms and cattle ranches. Indigenous Peoples I visited showed me the scars on their bodies caused by rubber bullets and the graves of their murdered leaders. No perpetrators of these crimes have been brought to justice. The local judges and police are complicit in attempts to drive the Guarani from their homes. Tekoha Taquara, an indigenous land I visited in Juti, has been served an eviction notice that was to be implemented the day I left Brazil. The first community I visited was attacked only three hours after I left. In the past few years, over 300 Guarani have been killed in land conflicts in Mato Grosso do Sul, not to speak of the high level of suicide rates because of desperation and hopelessness.

This failure is not only in direct contradiction to Brazil's obligations to protect its Indigenous Peoples under international law; it also contradicts the country's promises under the climate change treaty agreed upon in Paris. Brazil's Intended Nationally Determined Contribution outlines a commitment to reduce greenhouse gas emissions by 37 percent below 2005 levels by 2025, and to achieve zero illegal deforestation in the Brazilian Amazon by 2030.

Meeting these commitments will require Brazil to protect its Indigenous Peoples' land rights, as they are the proven best stewards of the world's largest rainforest. To date, Brazil has been the most successful country in decreasing its greenhouse gas emissions, largely as a result of titling indigenous lands. In the Amazon, deforestation rates are 11 times lower in community forests than outside. Brazil contains nearly half the world's remaining rainforest and sequesters 63 billion tons of carbon, much of it in legally recognized community forests.

The global aspiration of keeping warming below two degrees and protecting the earth for our children and grandchildren cannot succeed without forests, yet the very people we depend on to protect those forests are being murdered in droves. Illegal logging on indigenous lands persists, as do efforts to deprive Indigenous Peoples of their ancestral homes.

As mentioned, Brazil was an early leader in recognizing indigenous land rights, including protections for indigenous rights in its constitution and ratifying International Labour Organization Convention No. 169. But now the country has turned to large scale developments on indigenous lands as a means of buoying its economy, despite evidence that these strategies rarely result in sustainable development. Brazil's government is merely standing by, and have not done much to bring those who murder and maim the guardians of the forest to justice.

The impunity with which indigenous activists have been murdered must end. It is urgent that governments around the world – Honduras and Brazil included – take immediate action to protect indigenous rights activists peacefully protesting for legal rights to their own lands and territories. Global Witness recently released data showing that at least 109 environmental activists were killed in Honduras between 2010 and 2015; the murders are linked to a surge of destructive agriculture, mining, and dam projects that threaten the food sources, traditional livelihoods, and cultures of Indigenous Peoples, as well as the forests that we all rely on to mitigate climate change.

116 environmental activists were reported murdered globally in 2014; 40 percent of those killed were indigenous persons. I plead with governments around the world: do not allow Berta Caceres and hundreds of other indigenous leaders to have died in vain. Berta spent her life fighting for the rights of Indigenous Peoples to legally own the lands they have long called home, and to be free from destructive dams and other industrial projects. I am inspired and humbled by her courage and steadfastness. Let Berta and Nelson be the last in a long list of those who have given their lives in order to protect their homes and to protect the forests we all depend on.